Forgotten Sprouts Threw Trackers Off E. Coli Scent, Study Finds

People who forgot to mention they had eaten sprouts may have thrown disease trackers off the scent as they sought to trace the source of the deadly strain of E.coli that sickened more than 4,300 people and killed at least 50 in Europe this year, a study found. Photographer: Denis Doyle/Bloomberg

Oct. 27 (Bloomberg) -- People who forgot to mention they
had eaten sprouts may have thrown disease trackers off the scent
as they sought to trace the source of the deadly strain of E.
coli that sickened more than 4,300 people and killed at least 50
in Europe this year, a study found.

While a definitive genetic link remains elusive, three
separate lines of investigation point to sprouts as the means by
which the deadly O1O4:H4 strain of the bacteria was spread,
researchers led by Udo Buchholz at the Robert Koch Institute in
Berlin, Germany’s disease-control agency, wrote in the New
England Journal of Medicine yesterday. Their findings helped
pinpoint sprouts as the probable culprit in June.

Demand and prices for vegetables slumped across the
European Union after health officials mistakenly blamed
tomatoes, Spanish cucumbers and lettuce for the outbreak. The
error may have been because patients questioned about what they
ate at a restaurant linked to infections in the northern German
city of Luebeck forgot to mention sprouts, Buchholz and
colleagues wrote.

“The one dish that frequently exposed guests to sprouts
was the side salad, which contained tomatoes, cucumbers, three
sorts of leaf salads, and sprouts,” they wrote. “Sprouts may
have been the ingredient that visitors recalled least in such a
mixed salad.”

Sprouts have been linked to previous E. coli outbreaks in
the U.S. and Japan. Still, health officials in Germany neglected
to investigate sprouts because only a quarter of patients
mentioned them in a list of food they had eaten, the researchers
said.

‘Only Significant Variable’

Buchholz and colleagues conducted three studies in
parallel. The first involved asking patients hospitalized with
E. coli infection about their recent food consumption, and
comparing that with food eaten by uninfected people. It found
that “the only significant variable was sprouts.”

The second study identified 10 groups of diners who ate at
the restaurant in Luebeck between May 12 and 16. It found that
among 115 people who had been served sprouts, 31 fell ill,
compared with none of those who had not eaten sprouts.

The third investigation traced 41 clusters of infections to
a producer in Lower Saxony, who grew sprouts from seeds that
came from a “supplier X,” Buchholz and colleagues wrote,
without identifying either the producer or the supplier. A
European Commission task force said in July that the sprouts
were probably grown from fenugreek seeds imported from Egypt in
2009. The researchers still don’t know whether the seeds were
contaminated before, during or after export from Egypt.